将画布保存为 png C# wpf
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/21411878/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Saving a canvas to png C# wpf
提问by Daniel
So I am trying to take a snapshot of my canvas in WPF C# so that I can save it out as a png. The image saves incorrectly at present as it is including the left and top margins.
所以我试图在 WPF C# 中拍摄我的画布的快照，以便我可以将它保存为 png。图像目前保存不正确，因为它包括左边距和上边距。
This is what I have:
这就是我所拥有的：
create a rectangle for the size of the canvas. if canvas.Margin.Left and Top are set to 0 then the saved image is of the correct size but the offset still occurs and thus cuts the bottom and right edges. Being set the Margin.Left and Top still causes the offset to occur but the whole image is saved but at the wrong size (margin.Left + ActualWidth) rather than just ActualWidth
为画布的大小创建一个矩形。如果 canvas.Margin.Left 和 Top 设置为 0，则保存的图像大小正确，但偏移仍然存在，因此会切割底部和右侧边缘。设置 Margin.Left 和 Top 仍然会导致偏移发生但整个图像被保存但大小错误（margin.Left + ActualWidth）而不仅仅是 ActualWidth
Rect rect = new Rect(canvas.Margin.Left, canvas.Margin.Top, canvas.ActualWidth, canvas.ActualHeight);
double dpi = 96d;
RenderTargetBitmap rtb = new RenderTargetBitmap((int)rect.Right, (int)rect.Bottom, dpi, dpi, System.Windows.Media.PixelFormats.Default);
rtb.Render(canvas);
BitmapEncoder pngEncoder = new PngBitmapEncoder();
pngEncoder.Frames.Add(BitmapFrame.Create(rtb));
try
{
System.IO.MemoryStream ms = new System.IO.MemoryStream();
pngEncoder.Save(ms);
ms.Close();
System.IO.File.WriteAllBytes(filename, ms.ToArray());
}
catch (Exception err)
{
MessageBox.Show(err.ToString(), "Error", MessageBoxButton.OK, MessageBoxImage.Error);
}
回答by Jasti
Replace the first four lines with these lines
用这些行替换前四行
Rect bounds = VisualTreeHelper.GetDescendantBounds(canvas);
double dpi = 96d;
RenderTargetBitmap rtb = new RenderTargetBitmap((int)bounds.Width, (int)bounds.Height, dpi, dpi, System.Windows.Media.PixelFormats.Default);
DrawingVisual dv = new DrawingVisual();
using (DrawingContext dc = dv.RenderOpen())
{
VisualBrush vb = new VisualBrush(canvas);
dc.DrawRectangle(vb, null, new Rect(new Point(), bounds.Size));
}
rtb.Render(dv);
I have followed this article http://mcleodsean.wordpress.com/2008/10/07/bitmap-snapshots-of-wpf-visuals/(for more explanation) and able to save the canvas without margins.
我已经关注了这篇文章http://mcleodsean.wordpress.com/2008/10/07/bitmap-snapshots-of-wpf-visuals/（更多解释）并且能够在没有边距的情况下保存画布。
